/*
 Licensed to the Apache Software Foundation (ASF) under one
 or more contributor license agreements.  See the NOTICE file
 distributed with this work for additional information
 regarding copyright ownership.  The ASF licenses this file
 to you under the Apache License, Version 2.0 (the
 "License"); you may not use this file except in compliance
 with the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */

package org.apache.flink.connector.base.source.reader.mocks;

import org.apache.flink.api.connector.source.Boundedness;
import org.apache.flink.api.connector.source.Source;
import org.apache.flink.api.connector.source.SourceReader;
import org.apache.flink.api.connector.source.SourceReaderContext;
import org.apache.flink.api.connector.source.SplitEnumerator;
import org.apache.flink.api.connector.source.SplitEnumeratorContext;
import org.apache.flink.api.connector.source.mocks.MockSourceSplit;
import org.apache.flink.api.connector.source.mocks.MockSourceSplitSerializer;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.connector.base.source.reader.RecordsWithSplitIds;
import org.apache.flink.connector.base.source.reader.SourceReaderOptions;
import org.apache.flink.connector.base.source.reader.synchronization.FutureCompletingBlockingQueue;
import org.apache.flink.connector.base.source.reader.synchronization.FutureNotifier;
import org.apache.flink.core.io.SimpleVersionedSerializer;
import org.apache.flink.util.InstantiationUtil;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * A {@link Source} class for unit test of base implementation of source connector.
 */
public class MockBaseSource implements Source<Integer, MockSourceSplit, List<MockSourceSplit>> {
	private static final long serialVersionUID = 4445067705639284175L;

	private final int numSplits;
	private final int numRecordsPerSplit;
	private final int startingValue;
	private final Boundedness boundedness;

	public MockBaseSource(int numSplits, int numRecordsPerSplit, Boundedness boundedness) {
		this(numSplits, numRecordsPerSplit, 0, boundedness);
	}

	public MockBaseSource(int numSplits, int numRecordsPerSplit, int startingValue, Boundedness boundedness) {
		this.numSplits = numSplits;
		this.numRecordsPerSplit = numRecordsPerSplit;
		this.startingValue = startingValue;
		this.boundedness = boundedness;
	}

	@Override
	public Boundedness getBoundedness() {
		return boundedness;
	}

	@Override
	public SourceReader<Integer, MockSourceSplit> createReader(SourceReaderContext readerContext) {
		FutureNotifier futureNotifier = new FutureNotifier();
		FutureCompletingBlockingQueue<RecordsWithSplitIds<int[]>> elementsQueue =
				new FutureCompletingBlockingQueue<>(futureNotifier);

		Configuration config = new Configuration();
		config.setInteger(SourceReaderOptions.ELEMENT_QUEUE_CAPACITY, 1);
		config.setLong(SourceReaderOptions.SOURCE_READER_CLOSE_TIMEOUT, 30000L);
		return new MockSourceReader(
				futureNotifier,
				elementsQueue,
				() -> new MockSplitReader(2, true, true),
				config,
				readerContext);
	}

	@Override
	public SplitEnumerator<MockSourceSplit, List<MockSourceSplit>> createEnumerator(
			SplitEnumeratorContext<MockSourceSplit> enumContext) {
		List<MockSourceSplit> splits = new ArrayList<>();
		for (int i = 0; i < numSplits; i++) {
			int endIndex = boundedness == Boundedness.BOUNDED ? numRecordsPerSplit : Integer.MAX_VALUE;
			MockSourceSplit split = new MockSourceSplit(i, 0, endIndex);
			for (int j = 0; j < numRecordsPerSplit; j++) {
				split.addRecord(startingValue + i * numRecordsPerSplit + j);
			}
			splits.add(split);
		}
		return new MockSplitEnumerator(splits, enumContext);
	}

	@Override
	public SplitEnumerator<MockSourceSplit, List<MockSourceSplit>> restoreEnumerator(
			SplitEnumeratorContext<MockSourceSplit> enumContext,
			List<MockSourceSplit> checkpoint) throws IOException {
		return new MockSplitEnumerator(checkpoint, enumContext);
	}

	@Override
	public SimpleVersionedSerializer<MockSourceSplit> getSplitSerializer() {
		return new MockSourceSplitSerializer();
	}

	@Override
	public SimpleVersionedSerializer<List<MockSourceSplit>> getEnumeratorCheckpointSerializer() {
		return new SimpleVersionedSerializer<List<MockSourceSplit>>() {
			@Override
			public int getVersion() {
				return 0;
			}

			@Override
			public byte[] serialize(List<MockSourceSplit> obj) throws IOException {
				return InstantiationUtil.serializeObject(obj.toArray());
			}

			@Override
			public List<MockSourceSplit> deserialize(int version, byte[] serialized) throws IOException {
				MockSourceSplit[] splitArray;
				try {
					splitArray = InstantiationUtil.deserializeObject(serialized, getClass().getClassLoader());
				} catch (ClassNotFoundException e) {
					throw new IOException("Failed to deserialize the source split.");
				}
				return new ArrayList<>(Arrays.asList(splitArray));
			}
		};
	}
}
